Fuel cells generate electricity from hydrogen or various hydrocarbon fuels. In some fuel cells, an oxygen containing gas, such as air, is provided onto the cathode side of the electrolyte, while hydrogen or a hydrocarbon fuel is provided onto the anode side of the electrolyte. The fuel cell generates electricity through an electrochemical reaction. For example, in a solid oxide fuel cell, oxygen containing air is provided onto the cathode side of a solid ceramic electrolyte, while a hydrocarbon fuel is provided onto the anode side of the electrolyte.
Fuel cells operate more efficiently when the oxygen content of the inlet air is higher, primarily because the Nernst potential of the cell increases when the partial pressure of oxygen is higher. Therefore, the oxygen content of air being provided into the fuel cell is sometimes increased or enriched using various processes, including pressure swing adsorption (e.g., QuestAir Inc.'s Pulsar technology), oxygen-selective membranes (e.g., Boyer et al., J. Appl. Electrochem., p.1095, 1999), or magnetic separation devices (e.g., Nitta et al., U.S. Pat. No. 6,106,963, incorporated herein by reference in the entirety). However, these methods are generally inefficient because they require the use of power (i.e., electricity), thus decreasing the efficiency of the fuel cell and the power generation system.